Hi Terry, There is nothing fuzzy about 50w and 180 btu. Do the math yourself. I believe a 48" upright weighs in at around 400 lbs. If I am wrong please tell me. But certainly it weighs atleast 200 lbs. I mentioned water to define what a btu is and how *little* energy input we are dealing with. If you can make an "ice" piano let me know ok? (grin no need for humidity control there!) Woods make up a piano are considerably denser than water, therefore it would take longer to raise their temperature. Metal allows heat to transfer very quickly, and the plate is a pretty massive (or usually is), so it would take more to heat a plate than a similar amount of water. The energy "input" from a 50 watt rod is *only* 180 B.T.U's. Therefore a 50 rod can't increase the temperature of the whole piano much at all. It can and does affect the strings however. It's nice that you have measured the inside of the piano at 35 C. Where in the piano was your thermometer? Was it a min/max unit? Was it accurate? Did you have more than one measuring device? Was it an elcheapo from Radio Shack? What was the temperature outside the piano at the time? Please don't be so fuzzy Terry *grin*. And please don't be such a fussy reader! LOL The 50 rod is going to cycle more often than a 25. I believe that rapid cycling leads to a more even moisture content in the wood, and less effect on the strings. I have no proof of this. I would love to have some. At 09:21 AM 07/09/2001 -0400, you wrote: >What's with all this "fuzzy math"? I thought only American Presidents knew >how to use that? A piano is made of wood (admittedly with a small percentage >of water) and metal, and felt and glue, etc. It isn't made of water. So how >do you come to your conclusion based on a 400 lb. weight of a typical piano? > >I have measured temperatures inside a studio piano up to about 95 F (35 C), >when equipped with a 50 W rod and a standard calibration humidistat. The >temperature that the piano achieves will be dependant on two things: 1) the >maximum rod temperature - let's just assume it gets way hotter than we want >any piano, and 2) the rate at which heat energy escapes the interior of the >piano - either through direct transfer of air between the piano interior and >the room atmosphere (I would guess this is the primary route) and/or thermal >transmission through the case/soundboard/etc. It will not depend much on the >weight of the piano. The weight (wood weight, that is) will only affect the >total time required for the piano to come into equilibrium with the DC >system and room atmospheric conditions, when you have a properly sized DC >system. The weight of the piano could however affect the ultimate >temperature only in the case where you have an improperly sized DC system. > >I think. :-) > >Terry Farrell > >----- Original Message ----- >From: "Don" <drose@dlcwest.com> >To: <pianotech@ptg.org> >Sent: Sunday, July 08, 2001 11:16 PM >Subject: Re: Damp Chaser in old upright > > >> Hi Tony, >> >> A little point 50 watts is about 180 btu's. A British Thermal Unit is >> defined as the energy it takes to raise one pound of water one degree f. >> Assuming an upright piano weighs 400 lbs 180 btu's is *never* going to get >> the piano to 50 degrees C. (unless the room is 48 C already *grin*) >> >> Use the 50 watt rod with a humidistat. Things will be just fine. >> >> Regards, >> Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T. >> >> Tuner for the Saskatchewan Centre of the Arts >> >> mailto:drose@dlcwest.com >> http://donrose.xoasis.com/ >> >> 3004 Grant Rd. >> REGINA, SK >> S4S 5G7 >> 306-352-3620 or 1-888-29t-uner > > > Regards, Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T. Tuner for the Saskatchewan Centre of the Arts mailto:drose@dlcwest.com http://donrose.xoasis.com/ 3004 Grant Rd. REGINA, SK S4S 5G7 306-352-3620 or 1-888-29t-uner
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